861b28b965
New skills (14): - nestjs-best-practices: 40 priority-ranked rules (kadajett) - fastapi: Pydantic v2, async SQLAlchemy, JWT auth (jezweb) - architecture-patterns: Clean Architecture, Hexagonal, DDD (wshobson) - python-performance-optimization: Profiling and optimization (wshobson) - ai-sdk: Vercel AI SDK streaming and agent patterns (vercel) - create-agent: Modular agent architecture with OpenRouter (openrouterteam) - proactive-agent: WAL Protocol, compaction recovery, self-improvement (halthelobster) - brand-guidelines: Brand identity enforcement (anthropics) - ui-animation: Motion design with accessibility (mblode) - marketing-ideas: 139 ideas across 14 categories (coreyhaines31) - pricing-strategy: SaaS pricing and tier design (coreyhaines31) - programmatic-seo: SEO at scale with playbooks (coreyhaines31) - competitor-alternatives: Comparison page architecture (coreyhaines31) - referral-program: Referral and affiliate programs (coreyhaines31) README reorganized by domain: Code Quality, Frontend, Backend, Auth, AI/Agent Building, Marketing, Design, Meta. Mosaic Stack is not limited to coding — the Orchestrator serves coding, business, design, marketing, writing, logistics, and analysis. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
3.0 KiB
3.0 KiB
title, impact, impactDescription, tags
| title | impact | impactDescription | tags |
|---|---|---|---|
| Use Event-Driven Architecture for Decoupling | MEDIUM-HIGH | Enables async processing and modularity | architecture, events, decoupling |
Use Event-Driven Architecture for Decoupling
Use @nestjs/event-emitter for intra-service events and message brokers for inter-service communication. Events allow modules to react to changes without direct dependencies, improving modularity and enabling async processing.
Incorrect (direct service coupling):
// Direct service coupling
@Injectable()
export class OrdersService {
constructor(
private inventoryService: InventoryService,
private emailService: EmailService,
private analyticsService: AnalyticsService,
private notificationService: NotificationService,
private loyaltyService: LoyaltyService,
) {}
async createOrder(dto: CreateOrderDto): Promise<Order> {
const order = await this.repo.save(dto);
// Tight coupling - OrdersService knows about all consumers
await this.inventoryService.reserve(order.items);
await this.emailService.sendConfirmation(order);
await this.analyticsService.track('order_created', order);
await this.notificationService.push(order.userId, 'Order placed');
await this.loyaltyService.addPoints(order.userId, order.total);
// Adding new behavior requires modifying this service
return order;
}
}
Correct (event-driven decoupling):
// Use EventEmitter for decoupling
import { EventEmitter2 } from '@nestjs/event-emitter';
// Define event
export class OrderCreatedEvent {
constructor(
public readonly orderId: string,
public readonly userId: string,
public readonly items: OrderItem[],
public readonly total: number,
) {}
}
// Service emits events
@Injectable()
export class OrdersService {
constructor(
private eventEmitter: EventEmitter2,
private repo: Repository<Order>,
) {}
async createOrder(dto: CreateOrderDto): Promise<Order> {
const order = await this.repo.save(dto);
// Emit event - no knowledge of consumers
this.eventEmitter.emit(
'order.created',
new OrderCreatedEvent(order.id, order.userId, order.items, order.total),
);
return order;
}
}
// Listeners in separate modules
@Injectable()
export class InventoryListener {
@OnEvent('order.created')
async handleOrderCreated(event: OrderCreatedEvent): Promise<void> {
await this.inventoryService.reserve(event.items);
}
}
@Injectable()
export class EmailListener {
@OnEvent('order.created')
async handleOrderCreated(event: OrderCreatedEvent): Promise<void> {
await this.emailService.sendConfirmation(event.orderId);
}
}
@Injectable()
export class AnalyticsListener {
@OnEvent('order.created')
async handleOrderCreated(event: OrderCreatedEvent): Promise<void> {
await this.analyticsService.track('order_created', {
orderId: event.orderId,
total: event.total,
});
}
}
Reference: NestJS Events